In the formation of containers, such as can bodies formed from aluminum, it is conventional to use a tool pack assembly in which are usually mounted a redraw assembly including a redraw die, a plurality of ironing die assemblies, a domer and a stripper assembly. In such a process, a ram is moved into the redraw assembly and has a cup positioned thereon and then moves through the ironing dies to have the can body formed. The length of the stroke of the ram through the tool pack assembly is fairly long so that substantial alignment problems occur. In many instances, self-centering means are provided wherein the ironing die assembly is movably mounted for movement in radial directions in response to the location of the cup and the ram but also the self-centering means will move the ironing die assembly back to its original position when the external forces of the cup and the ram are removed. If the ram moves slightly out of alignment, this results in the movement of the ironing die assembly during each stroke of the ram so as to produce substantial wear and tear on the ironing die assembly. This wear and tear causes the shut down of the can body making system so that worn ironing die assemblies can be replaced by new ironing die assemblies.